B.W.
I can understand what you are feeling. I have a very active head strong 3 year old and fairly head strong 14 month old! The advice already given is all really good. I personally use time outs. My biggest backslide with my son was the 2-3 months right before and after my daughter was born. During this time I was too tired and did a lot of talking and was less consistent with doing. So, the most important thing is being consistent and stopping the action by doing. Timeouts and redirection typically work best. Time outs can be difficult with busy head strong kids, but most kids can get it as early as 18 months. It takes a lot of work to discipline and be consistent!